One of the many types of marine craft is the "inboard", a boat with a motor permanently mounted within the boat, the motor driving a shaft to which a propeller is connected exterior the hull of the boat. This shaft passes through a "shaft log" in the hull that functions as a shaft bearing as well as a shaft seal.
In these types of marine craft, it is common practice to pass the engine exhaust gases through a muffler to reduce the exhaust sound. Further, such exhaust systems generally utilizes a portion of the motor coolant water as a coolant for the muffler. This is normally accomplished by adding the water to the exhaust gases prior to entrance into the muffler. Then, a portion of this water exits with the exhaust gases from the rear of the marine craft.
A large number of mufflers for marine craft are known in the art. For example, several are identified and described in U.S. Pat. Nos. 2,360,429 issued to R. Leadbetter on Oct. 17, 1944; 2,498,979 issued to R. Bourne on Feb. 28, 1950; 3,296,997 issued to J. Hoiby, et al on Jan. 10, 1967; 4,713,029 issued to J. Ford on Dec. 15, 1987; 4,917,640 issued to C. Miles, Jr. on Apr. 17, 1990; 5,045,005 issued to C. Miles, Jr. on Sep. 3, 1991; 5,147,232 issued to C. Miles, Jr., et al on Sep. 15, 1992; and 5,259,797 issued to C. Miles, Jr., et al on Nov. 9, 1993. Of course, these patents cite prior patents generally relevant to the technology.
The complexity of the prior art mufflers varies from the simple construction of Hoinby ('997) to the various complex constructions of those of Miles ('640, '005, '232, '797). The complex designs are expensive to construct because of the numerous components and their arrangement. Further, as illustrated in Ford, the prior art mufflers are conventionally installed immediately adjacent the exhaust manifold of the engine. For this reason, the size and configuration is not particularly limited. While this is possible for most inboard craft, in very small craft of the type useful for a single boater such muffler systems occupy a significant proportion of the region near the engine. Thus, the boat must be of sufficient size to accommodate the muffler.
Therefore, it is an object of the present invention to provide an exhaust muffler for small marine craft that can be placed in the bilge area of the small craft to minimize the total size of the craft.
Another object of the present invention is to provide an exhaust muffler for small marine craft that can be placed in an extreme rearward portion of the bilge area adjacent the motor shaft and shaft log of the craft.
A further object of the present invention is to provide an exhaust muffler for small marine craft that has a top surface to conform to the undersurface of the craft deck, and a bottom surface to conform to the inner surface of the craft hull, including the shaft and shaft log, whereby a minimum space is taken up by the muffler within the bilge of the craft.
It is also an object of the present invention to provide a marine exhaust muffler that is both light in weight and is easily fabricated so as to minimize cost.
These and other objects of the present invention will become apparent upon a consideration of the drawings identified below, and a complete description thereof.